Upgrade npm packages (#2632)

Author: filiph

package.json

@@ -13,8 +13,8 @@
   },
   "devDependencies": {
     "canonical-path": "^1.0.0",
-    "diff2html-cli": "^2.6.0",
-    "firebase-tools": "^6.3.0",
+    "diff2html-cli": "^2.7.0",
+    "firebase-tools": "^6.8.0",
     "fs-extra": "^7.0.1",
     "gulp": "^4.0.0",
     "gulp-cli": "^2.0.1",